Propeller blade



Feb. 26, 1957 c. B. WRIGHT PROPELLER BLADE 2 Sheets-Sheet 1 Filed March 29, 1952 INVENTOR. [Hf/0H0 B. WING/1'7 m, We M014 Feb. 26, 1957 c. B. WRIGHT PROPELLER BLADE 2 Sheets-Sheet 2 Filed March 29, 1952 INVENTOR. a/frww B. HEIGHT United States PROPELLER BLADE Clifford B. Wright, Tipp City, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application March 29, 1952, Serial No. 279,372

8 Claims. (Cl. 170-159) stress concentration, fillet wells have been utilized. However, this expedient, while helpful, has failed to completely solve the problem. Accordingly, one of our objects is to provide a hollow propeller blade of two-piece construction wherein the bonded union between the two members is so disposed that it is subjected to minimum stress.

The aforementioned and other objects are accomplished in the present invention by locating the brazed joint or union along the neutral axis of the blade. Specifically, the hollow blade comprises two members, which may be symmetrical. Each member constitutes half of the blade and is provided with integral ribs or spars. The ribs and leading and trailing edges of the thrust members are copper brazed to each other along the neutral axis of the blade. In this manner the brazed joint is disposed in an area of minimal stress concentration.

Further objects and advantages of the present invention will be apparent from the following description, reference being bad to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Fig. l is an elevational view of a propeller blade constructed according to the present invention.

Fig. 2 is a cross sectional view taken along line 22 of Fig. 1.

Fig. 3 is a cross sectional view taken along line 3-3 of Fig. 1.

Fig. 4 is a cross sectional view taken along line 4-4 of Fig. 1.

Fig. 5 is a fragmentary elevational view of a propeller blade having modified shank and rib portions. 7

Fig. 6 is a view taken in the direction of arrow 6 in Fig. 5.

Fig. 7 is a sectional view taken on line 77 of Fig. 6.

Fig. 8 is a sectional view taken on line 8-8 of Fig. 6, with bearings added.

Fig. 9 is a sectional view of a rib portion taken on line 9-9 of Fig. 5.

Fig. 10 is an elevational view of a blade with a further modified shank portion.

Referring more particularly to Figs. 1 and 2 of the drawings, the hollow blade comprises two members 1 and 2 of identical configuration. The members 1 and 2 are preferably composed of a light metal or alloy, which may be cast, forged, extruded, or manufactured in any other suitable manner. As the members 1 and 2 are identical, a detailed description of one is deemed to be sufficient.

atent 2,7323% Patented Feb. 26, 1957 The member 1 has a somewhat convex exterior sur face throughout the major portion of its length. It is provided with a leading edge 3 and a trailing edge 5. Between the leading and trailing edges, the member 1 is provided with a pair of inwardly projecting ribs or spars 7 and 9, which converge from the root end to the tip end. The number of ribs provided may vary with the rigidity desired. The inner faces of the leading edge, the trailing edge, and the ribs terminate in alignment with each other, and are bonded to the corresponding faces of the member 2 preferably by means of copper brazing to form an airfoil section. The line of division 10 between the members 1 and 2 is at the transverse neutral axis of the blade. Stress concentration along the neutral axis is of a minimum amount. Accordingly, the brazed union between the members 1 and 2 is not subjected to any substantial stress, and in this manner, the blade has an extremely high fatigue endurance.

The shank portion of the blade is provided by semicylindrical portions of members 1 and 2, which are formed by the merging of the ribs 7 and 9 with the leading and trailing edges 3 and 5, respectively. The ribs 7 and 9 extend substantially the entire length of the blade and provide between them a cavity that is substantially elliptical. The contiguous surfaces of the members 1 and 2 are securely united by copper brazing or any other welding material. As each half of the blade may be symmetric with respect to the other half, the blades can be easily manufactured.

Referring to Figs. 5, 6 and 7, a propeller blade split at the neutral axis and having a modified shank portion 11, is capable of sustaining greater shear loads. The cylindrical shank portion 11 of the blade is comprised of two halves joined at the neutral axis 10. In order that the shank 11 may better sustain the imposed shear loads thereon during rotation of the propeller blade, semicircular notches 13 in member 1 and 14 in member 2 cooperate to provide a plurality of circular holes along the neutral axis 16 of the transverse section of the blade.

Disposed in these holes are radially extending pins 12, the pins being bonded to the circumferential portion of the holes, thereby providing a shank portion 11, which will sustain greater shear loads.

In order to prevent the direct application of bearing loads upon the brazed union between the two semicylindrical shank portions 1 and 2, the exterior surface of the shank in the region of the brazed union may be relieved at 15, as is shown in Fig. 8. The relieved areas 15 are such that the ball bearings 16, which are used to rotatably journal the blade in a hub socket, transmit the load to the shank portions on either side of the brazed union, thereby preventing any bearing loads on the brazed joint itself.

In order to provide more brazing area between the contiguously disposed surfaces of the ribs 7 and 7', Fig. 9, the end portions thereof may be provided with 0ppositely disposed flanges 17 and 17, respectively, which are contoured to prevent stress concentration. As a further means of providing a greater bonding area be tween the ribs, one of the ribs 7 may be notched at 19 and its cooperating ribs 7' may have a projecting tongue portion 19 cooperating therewith. In this manner the brazing area between the two ribs is substantially increased.

A further means of constructing the shank portion 11 of the blade so that it will sustain greater shear loads, is by providing each of the members 1 and 2 with a series of cooperating notches or teeth 21 and 22, respectively, as shown in Fig. 10. The teeth or notches are so formed on one member that they intermesh or interlock with the teeth on the other member.

While the embodiments of the present invention as .5 herein disclosed, constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. A hollow metal propeller blade comprising, a pair of halves symmetrical to each other on opposite sides of a plane located longitudinally of the blades and including the area of contiguous surface of each half which plane contains the transverse neutral axis in the spanwise direction therebtween, each half having a semi-cylindrical shank section and an integral airfoil section, each said airfoil section having a leading edge mating surface, a trailing edge mating surface, a tip end mating surface and an inwardly projecting rib portion which is coextensive with one of the said edge surfaces and which merges into said edge surface adjacent the shank portion, said halves being arranged so that mating surfaces of said tip, leading and trailing edges, said shank section, and said rib portions are disposed in contiguous relation to each other, means uniting said halves'at the contiguous portions thereof, and interlocking means between the shank sections lying between the circumferences of the shank sections and complementing said uniting means and cooperable with said uniting means such that said sank sections may better sustain the shear loads imposed thereon during rotation of the propeller blade.

2. A hollow metalpropeller blade comprising, a pair of halves symmetrical to each other on opposite sides of a plane located longitudinally of the blades and including the area of contiguous surface of each half which plane contains the transverse neutral axis in the spanwise direction therebetween, each half having a semi-cylindrical shank section and an integral airfoil section, each said airfoil section having a leading edge mating surface, a trailing edge mating surface, a tip end mating surface and a plurality of inwardly projecting integral rib portions, one of said rib portions merging into and being coextensive with the leading edge surface adjacent the shank section extending therefrom to the tip end of said blade, another of said rib portions merging into and being coextensive with the trailing edge surface adjacent the shank section extending separately therefrom to the tip end of said blade, said halves being arranged so that mating surfaces of said leading and trailing edges, said shank section and said rib portions are disposed in contiguous relation to each other, and means uniting said halves at contiguous portions thereof including interlocking means in said shank sections lying between the circumferences of the shank sections and complementing said uniting means and cooperable with said uniting means such that said shank sections may better sustain the imposed shear loads thereon during rotation of the propeller blade.

3. The combination set forth in claim 1 wherein said rib portions are contoured to provide oppositely extending flanges to increase the contiguous surface area therebetween.

4. The combination set forth in claim 1 wherein one of said rib portions has a notch therein and the other of 4 said rib portions has a projecting tongue, said notch and tongue cooperating to provide a greater area of "union between said rib portionspand a pair of oppositely-disposed contoured flanges to increase the contiguous surface area.

5. A hollow metal propeller blade, comprising, two members joined at a common plane of longitudinal symmetry therebetween from the tip end to the shank end thereof, said shank ends being provided with a plurality of semi-circular notches lying radially between the circumferences of the shank ends mid symmetrically spaced along contiguous shank surfaces forming a plurality of circular holes along the plane of symmetry, and a plurality of radially extending pins bonded to the circumferential portion of the holes thereby. providing a shank portion which will sustain greater shear loads.

6. The propeller blade of claim 1 wherein said interlocking means comprises a plurality of interlocked teeth along a portion of said neutral axis to sustain the shear loads imposed thereon 7. .The propeller blade of claim 1 wherein the shank sections of said halves are provided with longitudinally extending relief areas removed from the exterior surface of the shank end along opposing edge portions on'either side of the plane of symmetry of said blade to prevent bearing loads to be transmitted to said means uniting said halves of said blade.

8. .The propeller blade of claim 1 wherein said inter locking means include notches in said shank sections symmetrically located in each blade half relative to the plane of longitudinal symmetry so as to form complementary portions of holes with said continguous shank sections, and :a plurality of radially extending pins disposed in the holes modifying said shank section for sustaining greater shear loads.

References Cited in the file of this patent UNITED STATES PATENTS 411,637 Batchelor Sept. 24, 1889 647,468 Brown Apr. 17, 1900 1,450,935 Anderson Apr. 10, 1923 1,937,966 Junkers Dec. 5, 1933 2,231,888 Couch Feb. 18, 1941 2,326,430 Blanchard .Aug. 10, 1943 2,329,366 Weill et al. Sept. 14, 1943 2,457,202 Brady Dec. 28, 1948 2,482,217 Sacchini Sept. 20, 1949 2,487,860 Enos Nov. 15, 1949 2,493,139 Heath Jan. 3., 1950 2,512,264 Brauchler June 20, 1950 2,514,525 Stulen July 11, 1950 2,561,705 Lochman July 24, 1951 2,604,569 Denneen July 21, 1952 2,615,236 Stulen Oct. 28, 19.52 2,659,444 Stanley Nov. 17, 1953 FOREIGN PATENTS 363,532 Germany Nov. 10, 1922 

